1. Field of the Invention
The present invention relates to a control apparatus for regulating perimeter heating or cooling of a building according to the direction and magnitude of heat flow through building elements whose exterior surfaces are exposed to outside weather conditions.
2. Description of the Prior Art
The usual central heating system for a building heats or cools the building interior in accordance with temperatures sensed within the building interior. The temperatures established by such a system are comfortable to those located at the building core, but often not to those located at the building perimeters. This is because heat losses to the exterior and heat gains from the exterior are most noticeable to occupants of the building perimeter.
Various systems exist in the prior art to bring the temperature of the building perimeter into closer correspondence with the temperature of the building core. Baseboard heaters or coolers have been used adjacent the exterior building walls to heat or cool the perimeter according to various sensed conditions. One system of the prior art operates the baseboard temperature change system in accordance with control signals provided by an air temperature sensor located on an interior surface of an exterior wall of the building. This type of system is unsatisfactory because the sensor is responsive only to the inside temperature near the wall, and is influenced by the wall temperature, which can lag by many hours the actual changes in the heat loss from or heat gain to the perimeter. For example, a rapid change in perimeter heating or cooling requirements at windows can occur because of a change in the relative position of the sun, or because of a rapid change in wind velocity. Wall mounted sensors do not respond rapidly enough, and in the proper amount, to compensate for such changes.
Another system of the prior art uses a plurality of temperature sensors whose output is combined in a particular way to regulate the perimeter heating and cooling system. One of the sensors is located to sense inside air temperature at the building core, another is located to sense outside air temperature, another located to sense the temperature adjacent the perimeter temperature change system, and others are located to respond to the radiant heat of the sun. Despite the sophistication and complexity of such a system, it still does not operate the perimeter heating and cooling system in a manner accurately anticipatory of the actual changes occurring at the building perimeter as a result of environmental conditions.
Yet another prior art system involves simply measuring the outside air temperature and varying the heating and cooling proportionally, ignoring the effects of sun and wind conditions. This system has also failed to meet the problems of perimeter temperature control.